When I think about it I DONT want to think about how many pairs of speakers I have had. Particularly when I started chasing my tail over the next latest and greatest thing. I was often changing speakers when I heard a difference in the sound rather than a sustained improvement. I was also listening for the speaker rather than the music that played through it. Of all the speakers that I once owned on the audio merry-go-round the pair that was most memorable was the Equation 25s from Belgium. Very rare and hard to find used, the owner of Equation retired, but of all that Ive owned, they were both the best and the ones most missed. Runner up goes to Klipsch Cornwalls, with Bob Crites crossovers and wiring. They are a great, great speaker that stands the test of time and give you infinite possibilities with amplification. I associate them with experiments with all different types of tube gear over a 3-year period.
Speakers that I both currently own and plan to hold onto for the long-haul in descending order of preference:
JBL 4312As Studio Monitors: A wonderful full-range monitor that was the basis for many recording during the 80s. To my ears, they are speakers I keep coming back to for their balance and honesty or reproduction.
Dynaudio 1.3 SEs: Ive had both the SEs and the MKIIs and enjoyed them both. Are they better in absolute terms than the JBLs? Im not sure. I think that I like the JBLs better as they go lower and communicate more detail. Certainly the Special 25s are better but they are exponentially more money too with large diminishing return for incremental gains.
Phillips Spectron SP-40s: Built around the same time as the JBLs they were, I believe, Phillips all out attempt to build a competitor to the JBL 4312s. Like the JBLs they are a 3-way design with a dome midrange. A sleeper of a speaker but some vintage audio collectors are seeking them out, I heard about them from a friend I trust, found a pair a year later and have been amazed by their performance- they come very close to the aforementioned JBLs giving only the slightest away in transparency to the studio monitor.
Dynaco A25s: I have a modified pair with Mundorf caps and upgraded wire and binding posts and they sound incredible. I know that it is a cliché but they get out of the way of the music just like both the JBLs and the Spectrons.
From this list, you can tell that I like vintage monitors but a priority for me for the long-term is a speaker that is as neutral is possible that does not draw attention to itself vs. the music playing though it. Well chosen vintage speakers with modified caps, wiring, and binding posts compete very closely with the most current speakers today in all but imaging, and better many in tonal reproduction.